1. Field of the Invention
This invention relates to lead-in plugs and particularly liquid tight plugs intended for installation in a bore of a housing wall to seal the bore while providing access through the wall for cable or wire or for tang-like plugs which are to be connected to electrical devices housed within the housing defined by the wall, and particularly for installations where the housing is to be filled with a casting resin.
2. Prior Art
Various methods and means for connecting electrical apparatus housed in housings which are not filled with casting compound are known. For example, when using stranded or cable conductors, generally the conductor is guided over the housing upper edge and secured to the lateral wall of the housing. In the case of large plastic housings, holes may be drilled in the housing wall. The stranded conductors are then pulled or threaded through the drilled holes and cemented into the housing interior. On the other hand, small plastic housings which are fabricated in large numbers may be provided with bores which have elastic sealing lips injected in place. Such constructions, however, require very high initial tooling costs.
In the case of metal housings, the diameter tolerance of the connecting cable may be compensated for by means of beaded or flanged tubular rivets impressed in the bores of the housing wall. Such construction necessitates expensive special riveting machines and, furthermore, known methods of installing and fabricating the rivets are relatively expensive. It is also known to inject plugs or to press or cement them respectively in housing fittings or sockets.
In any case, the prior art has not provided interchangeability between stranded connector connections and plug connections. Moreover, the provision of mass produced seal plugs has not been successfully accomplished.